As you may have noticed, many of these simulations could possibly help you learn something. Maybe. Now, I'm not actually a professional in teaching (and also don't have official education on the physics/math of my simulations, feel free to mod these for your needs), and many of these simulations don't repersent reality fully (they're 2d), but they might still be useful somehow. Do note that many of these simulations don't work that well on a chromebook: they work, but can randomly crash. Because of that, here's some ideas for each thing:

gravity simulator

Gravity simulator isn't fully realistic, and for a basic course, something built by someone with more expertise (like particle sandbox) would work way better, however it's also able to simulate many things that aren't even space related (via links and the lack of merging), like basic fluid dynamics or 2d mechanics. In fact, it should be possible to make a gear. It also has a save/load system, which you might be able to use to let students send/share their designs, although last time I pasted a savecode onto google docs on a chromebook, it crashed. However, it is the only actually kinda useful thing here, since SST (space simulation toolkit, the closest already-existing hing I know of to gravity simulator) isn't free, and SpaceSim, while apparently working on a chromebook and being free, would probably melt a chromebook or something.

chemistry simulator

This one is not really realistic at all... but it can still simulate ionic lattices, basic chemistry, and isn't too bad as long as there's no lone pairs. However, for any chemical reactions... well, just pretend that it's another universe. It's a 2d simulation anyways. Also, if you don't need charge or different sizes, just use interactive molecular dynamics (which is much better for that).

artificial life attempt

This one might be able to teach emergence, but I don't see any way it's that useful, since the attraction/repulsion parameters barely make life... also, actual life would probably require more particles than a chromebook can handle.

fluid dynamics simulator

Energy2d by concord consortium exists. Just use that. It can do everything my simulation can do and much more. I guess you could still use its code to teach coding.

4d shapes viewer

4-dimensional geometry might somehow be important to something you're teaching, but IDK. Also, it might be a bit confusing, end up glitching out other games and killing them, or just crash (which it rarely does on a chromebook, somehow). However, it might be useful for complex numbers, as a complex number graph should be 4d (Re(z),Im(z),Re(f(z)),Im(f(z))).

And onto the others, not based on gravity simulator:

TOG

...what do you expect?

teaching with this stuff

You're already there.

symbolic regression

Its code actually has an abstract syntax tree class, and it could teach students that normal machine learning isn't the only way to teach a machine, but aside from that it's not too useful unless you need weird approximations of pi.

a plain text area for your convience

Not quite sure how you'd learn from this unless you don't know how to type (somehow). At best, could be for note-taking, but Google Docs exists anyways.

hilberto the hilbert curve

It's practically just a weird spongey epilepsy warning. I can't think of any good use of this in a classroom.

However, even if my simulations can't teach that much themselves, if your students are interested in coding and/or physics stuff, maybe have them mod a simulation here. Just, make sure to save that version, just in case